'Letter' in the Bible

So the king of Aram said, Go then; and I will send a letter to the king of Israel. And he went, taking with him ten talents of silver and six thousand shekels of gold, and ten changes of clothing.

And he took the letter to the king of Israel, in which the king of Aram had said, See, I have sent my servant Naaman to you to be made well, for he is a leper.

But the king of Israel, after reading the letter, was greatly troubled and said, Am I God, to give death and life? why does this man send a leper to me to be made well? is it not clear that he is looking for a cause of war?

Straight away, when you get this letter, seeing that your master's sons are with you, and that you have carriages and horses and a walled town and arms;

Then he sent them a second letter, saying, If you are on my side, and if you will do my orders, come to me at Jezreel by this time tomorrow, with the heads of your master's sons. Now the king's seventy sons were with the great men of the town, who had the care of them.

And when the letter came to them, they took the king's sons and put them to death, all the seventy, and put their heads in baskets and sent them to him at Jezreel.

And Hezekiah took the letter from the hands of those who had come with it; and after reading it, Hezekiah went up to the house of the Lord, opening the letter there before the Lord.